1. Field of the Invention
The present invention relates to apparatus for pasteurizing or heat treating fluid products for consumption by animals or humans.
2. Description of the Relevant Art
Since the dawn of history, various methods and apparatus have been devised for the heat treatment of foodstuffs for human and animal consumption, including cooking, pasteurization and sterilization. Both pasteurization and sterilization have been used with milk and related products. U.S. Pat. No. 4,310,476 provides in columns 1 to 5 an extensive discussion of pasteurization and sterilization of milk, which is incorporated herein by reference. Column 30 of the same patent identifies legal U.S. standards for milk pasteurization, which are also incorporated by reference.
Dairy farmers and other producers of foodstuffs such as milk are often required to transport their produce to central plants for processing including pasteurization or sterilization and packaging. In less advanced countries, modern processing plants may be unavailable or inaccessible, so that dairy products must be utilized locally, with whatever processing is available. Excess milk and related products may be used on the farm for feeding calves or other livestock, but may spoil or transmit disease if not pasteurized. There is an apparent need for economical apparatus for pasteurizing such milk or related products on site to permit safe use for feeding calves and the like. There is also a need for simple and economical apparatus for processing milk at or near the source in less advanced countries for both human and animal consumption.
Numerous patents disclose methods and apparatus for sterilizing or pasteurizing food directly or enclosed in containers. A number of these patents are disclosed in the background section of Applicant's U.S. Pat. No. 6,276,264. Additional patents relevant to the present invention are discussed below.
U.S. Pat. No. 4,788,871 discloses a probe for monitoring temperature and pressure in a thin-walled plastic container (i.e., a food container) which is undergoing a pasteurizing or sterilizing operation in suitable apparatus. The apparatus includes a pressurized vessel connected to water circulation and temperature control means.
U.S. Pat. No. 5,519,189 discloses the use of an external pump, heater and control apparatus for heating a drum (and contents to be heated) by circulating heated water (or other liquid) through a bath in a tub surrounding the drum.
U.S. Pat. No. 6,437,295 discloses a “lotion heating system” including an open container holding a closed bottle of lotion in a bath of water, the container, bath and lotion bottle being heated by an electrical heater with multiple levels of heating power.
U.S. Pat. No. 5,773,795 discloses an electric warming device using a “P.C.” Heating element and a water bath. Thermostatic temperature control is discussed.
U.S. Pat. No. 4,479,423 discloses a “Continuous-Flow Apparatus For Pasteurizing Batches of Product,” including heating and cooling coils in heat-exchange contact with a conduit for milk or other products to be pasteurized. The apparatus includes a cleaning system.
U.S. Pat. No. 5,671,662 discloses a pasteurizer for food products including a tank having an agitator to agitate the liquid therein, the agitator being set into a recess at the bottom of the tank and powered by an external motor.
U.S. Pat. No. 5,977,521 discloses an electric heater for a chafer, normally including a chafing dish, wherein the heater is positioned against the bottom of the chafing dish by a spring.
U.S. Pat. No. 6,189,440 discusses a continuous flow pasteurizer comprising a first tank and a second tank interconnected by a pasteurization conduit. Fluids are heated to a desired temperature in a first section of the conduit and held at this temperature while flowing through a second section of the conduit.
Most of these patents disclose apparatus and methods for the continuous processing of milk or other foodstuffs, and most of these systems are complicated and expensive. There remains a need for simple, economical apparatus for batch processing of various types of milk and components thereof on dairy farms and the like.
While it has long been known that pasteurization is an important tool in preventing the spread of disease through milk and other food products, pasteurization of colostrum has been a more delicate matter. Colostrum is known as the “first milk” of most mammals. It is extremely high in nutritional content, but more importantly, it carries the first “vaccine” for the newborn in the form of various immunoglobulins (Ig). These proteins confer immunity to the newborn by being absorbed directly into their bloodstream. Adequate levels of these immunoglobulins (Ig) must be consumed by the newborn at a very early age, usually within hours of birth. Due to the high level of protein in the form of Ig, the pasteurization procedure must be carried out in a manner which preserves these proteins while still adequately pasteurizing. There has been some success in this field over the past couple of decades, but a commercial unit has not been widely available to do quantities large enough for the average dairy.
The drawbacks of current systems include the following: Many pasteurizers are high temperature short time (HTST) systems that rapidly bring the product to a high temperature, hold it there for a short time and then rapidly cool the product once again. These systems cause rapid degradation of the Ig, often lowering the level below that required to impart immunity to the newborn. Also at these high temperatures, the end product is greatly thickened in consistency. This thickening prevents delivery of the colostrum to the newborn animal. For these reasons, these HTST systems will not handle the product well and often become plugged to the point of requiring disassembly for cleaning them. Other manufacturers have designed thermos systems in hot water baths and small table top models that will pasteurize the colostrum by bringing it to a lower temperature and holding it there for a longer period of time. While this methodology does a much better job of preserving the Ig, there are still considerable drawbacks. These systems are typically labor intensive due to the lack of automation. The operator must keep the product stirred for even heating. The temperature control is often primitive and involves hand held thermometers or loosely calibrated thermostats such as those used on an electric skillet. The other main disadvantage is the small volume that most of these will handle. Two gallons seems to be the capacity of some of the larger units. The average cow will yield more than this in her first milking, which makes the unit once again labor intensive for most cow (bovine) or goat (caprine) dairies. There is a particular need for a pasteurizer which can optimize the use of this scarce resource.